Superabsorbent polymers (SAPs) are used in a variety of industrial and consumer applications, ranging from disposable hygiene products to cable water blocking. SAPs are mostly commonly manufactured by polymerization of acrylic acid. Acrylic acid production is a large industry that uses variety of methods having a range of cost efficiencies and yielding acrylic acid of varying purity. Given the size of the acrylic acid market and the importance of downstream applications of acrylic acid, there is a need for methods for producing acrylic acid with increased efficiency.
Methods have been described where beta propiolactone (BPL) is converted to acrylic acid (AA) by heating in the presence of water or alcohols which act as catalysts to open the BPL to hydracrylic acid (3-hydroxy propionic acid) or hydracrylic acid esters, respectively. However, these methods are ill-suited to the production of glacial acrylic acid (GAA) because the water or alcohol used to catalyze the reaction can contaminate the acrylic acid stream.
Another route to produce acrylic acid from beta propiolactone (BPL) first polymerizes BPL to poly(propiolactone) (PPL), which is then isolated and fed into a pyrolysis unit where it thermally decomposes to acrylic acid. However, this multi-step process requires extensive unit operations and is capital intensive.
Thus, methods to address such problems in the art are desired.